Why are Neodymium Magnets so strong?

 Neodymium magnets are the strongest type of permanent magnets because they combine a specific atomic alloy, a unique crystal structure, and high resistance to losing their magnetism. [1, 2, 3, 4, 5]

The Special Alloy and Crystal Structure

The Formula: The magnets are made from an alloy of neodymium, iron, and boron with the chemical formula Nd₂Fe₁₄B. [1, 2]
Iron's Power: Iron provides most of the actual magnetic strength (the large magnetic moments), but pure iron loses its alignment easily. [1, 2]
Neodymium's Role: Neodymium (a rare-earth element) has unpaired electrons in its outer shell that create a massive "magnetocrystalline anisotropy". This means the crystal structure forces all the iron atoms to point their magnetic fields in one strict, unyielding direction. [1, 2, 3]
Boron's Stability: Boron acts as a glue or stabilizer in the crystal lattice, making the structure tough and hard to disrupt.

Key Magnetic Properties

High Remanence: They have a high remanence, meaning the strength of the magnetic field they project is extremely dense and powerful. [1]
High Coercivity: They possess high coercivity, which is a strong resistance to demagnetization. They lock their internal magnetic domains in place so the magnet does not weaken over time. [1, 2]
High Energy Product: Their maximum energy product—the total amount of magnetic energy packed into a given volume—is up to ten times greater than traditional ceramic or ferrite magnets. This allows a tiny neodymium magnet to do the job of a massive traditional magnet. [1, 2]